1. Field of the Invention
The present invention relates to a microphone system and a microphone apparatus. More particularly, the present invention relates to a microphone system including a main unit for controlling the entire system and microphone apparatuses, having cascade connections from the main unit assuming the main-unit side to be upstream and the opposite side to be downstream, for transmitting sound signals in sequence, and to the microphone apparatus thereof.
2. Description of the Related Art
Up to now, conference systems, which allow holding a conference among many places by transmitting and receiving sound, video, etc., through a plurality of terminals installed in many places such as remote places, etc., have been built as represented by a television-conference system.
FIG. 8 is a configuration diagram illustrating an example of a known conference system among many places.
In the known conference system, terminal units 500, 510, and 520 disposed at each place are connected to a network, and sound data and video data are exchanged. Each terminal unit, for example the terminal unit 500 includes a microphone 501 for collecting sound and a speaker 503 for outputting sound. Similarly, the terminal unit 510 includes microphones 511 and 512 connected in a cascade and a speaker 513, and the terminal unit 520 includes microphones 521 and 522 and a speaker 523. In such a conference system, sound obtained by the microphone 501 is sound processed by the terminal unit 500, transmitted to the terminal units 510 and 520, and then output from the speakers 503, 513, and 523 of each of the terminal units, respectively.
Up to now, sound data or video data transmitted and received among the terminal units 500, 510, and 520 were transmitted and received through an unillustrated multi-point controller. However, a conference system which makes the multi-point controller unnecessary by transferring sound data or video data to the next stage in sequence among the terminal units connected in a cascade has been proposed (for example, Japanese Unexamined Patent Application Publication No. 2000-23129 (paragraph numbers [0012] to [0038], FIG. 1)). In a conference system having such a configuration, each terminal unit adds sound collected by a self-microphone to the sound data obtained from the previous stage in order to output the sound to the subsequent terminal unit, and outputs the sound produced by adding self-sound data to the obtained sound data to a speaker. Thus, it becomes possible to carry on a conversation simultaneously.
Also, for a microphone to be connected to a terminal unit, there is a microphone apparatus, such as microphones 511 and 512 of the terminal unit 510, which converts the voices of the speakers collected by individual microphones connected in a cascade into sound signals and generates a mixed sound signal obtained by mixing the self-sound signal with the sound signals from the other microphones connected in a cascade (for example, Japanese Patent Publication No. 3379313 Specification (paragraph numbers [0016] to [0018], FIG. 2)).